In 1969, Poppy is seen painting her nails orange. In all of the present day shots in which Poppy is seen, there is something orange somewhere in the frame.
The idea from Carmelita came from an idea for a documentary that Christy Stevens pitched in her documentary class. Upon further researching her documentary, she found that the story she heard was false. She then turned the story into the narrative that became Carmelita.
The car was made to look rusty by using water-color paint. When the car is parked outside of the storage facility when Poppy and Cooper first open the door, the entire crew - excluding the camera operator and director - was standing just off-screen holding a tarp over the rear end of the car to prevent the paint from washing off.
The producer, Steven Crocker, and both of the directors, Jake Brinn and Christy Stevens, have cameos in Carmelita. When Calvin and Poppy lie in the back of the car, Calvin holds Poppy's hand - but the hands are not those of Sam Dimirsky (Calvin) or Joanna Whicker (Poppy), they are actually the hands of Steven Crocker (producer) and Carleigh Pappas. Later in the film, when older Poppy is sitting in the living room with Whit and Cooper, there are pictures on the wall - Christy Stevens (co-director) and Jake Brinn (co-director) appear in the photos. Christy is photographed as the woman Calvin ended up marrying, Whit's mother. Jake is photographed as a soldier with Calvin on a hillside that is supposed to be in Vietnam.